Nox4 and the Redox-Regulation of MKPs in Monocyte Recruitment and Atherosclerosis

描述(由申请人提供)：趋化因子驱动的单核细胞向内皮下间隙的迁移是动脉粥样硬化形成中一个基本的和限速的过程。我们的初步数据显示，这一过程受到代谢应激的失调，单核细胞对趋化因子的反应性增加似乎加速了动脉粥样硬化斑块的发展。我们现在已经在单核细胞中发现了一种新的硫醇氧化还原敏感机制，当代谢紊乱导致调节失调时，它就会“启动”，并将单核细胞转变为高度趋化的前动脉粥样硬化表型。此外，我们还发现最近发现的单核细胞NADPH氧化酶4是单核细胞启动的介体。我们认为，代谢应激诱导的NOX4和随后增加的H_2O_2在单核细胞中促进了S谷胱甘肽基化和丝裂原激活的蛋白激酶磷酸酶(MPK)的失活；MKPs是导致磷酸化ERK和磷酸化p38MAPK失活的酶，这两个MAPK通路是MCP-1诱导的单核细胞黏附和迁移的两个主要途径。我们假设单核细胞MPK代表了代谢紊乱引起的氧化应激和动脉粥样硬化病变形成之间的一种新的、关键的机制联系。我们的研究支持一种新的范式，即单核细胞启动和功能障碍是动脉粥样硬化形成的早期主要因素。我们在这里提出的研究旨在测试这一范式并阐明其潜在的分子机制。具体目标1：确定丝裂原活化蛋白激酶磷酸酶(MKP)在单核细胞黏附、趋化和重新聚集到动脉粥样硬化病变中的氧化还原调节中的作用。特异性目标2：确定蛋白质-S-谷胱甘肽基化在单核细胞募集和动脉粥样硬化病变发展中的作用。具体目标3：确定单核细胞NOX4在单核细胞启动和动脉粥样硬化形成中的作用。

DESCRIPTION (provided by applicant): Chemokine-driven transmigration of monocytes into the subendothelial space is a fundamental and rate- limiting process in atherogenesis. Our preliminary data show that this process is dysregulated by metabolic stress and that increased monocyte responsiveness to chemokines appears to accelerate atherosclerotic plaque development. We have now uncovered a novel thiol redox-sensitive mechanism in monocytes that upon dysregulation by metabolic disorders, "primes" and transforms monocytes into a hyper-chemotactic pro- atherogenic phenotype. In addition, we have found that the recently discovered monocytic NADPH oxidase 4 is a mediator of monocyte priming. We propose that metabolic stress-induced Nox4 and the subsequent increase in H2O2 formation in monocytes promote the S-glutathionylation and inactivation of mitogen-activated protein kinase phosphatases (MPKs); MKPs are the enzymes responsible for the deactivation of both phospho-ERK and phospho-p38MAPK, the two principal MAPK pathways mediating MCP-1-induced monocyte adhesions and migration. We hypothesize that monocyte MPKs represent a novel, critical mechanistic link between oxidative stress induced by metabolic disorders and the formation of atherosclerotic lesions. Our studies support a new paradigm implicating monocyte priming and dysfunction as an early primary contributor to atherogenesis. The studies we propose here aim to test this paradigm and elucidate the underlying molecular mechanisms. Specific Aim 1: Determine the roles of mitogen-activated protein kinase phosphatases (MKP) in the redox regulation of monocyte adhesion, chemotaxis, and recruitment into atherosclerotic lesions. Specific Aim 2: Determine the roles of protein-S-glutathionylation in monocyte recruitment and the development of atherosclerotic lesions. Specific Aim 3: Determine the roles of monocytic Nox4 in monocyte priming and atherogenesis.